Double Wings wasn't on my list, but I indeed found something to improve with the soundlatch handling. The sound writes are obfuscated through a DECO 104 protection ASIC, which used to be the reason the game was not working in MAME for a long time. That turned out to be a red herring; it looks more like the sound code wants command writes to take priority over a constant barrage of timed interrupts from the YM2151. The old code was acknowledging soundlatch writes on every IRQ, no matter what the source, which is probably not how that was supposed to work. Some sound-related mysteries still exist, but overall it looks like a slight improvement.
|